Last week I tried a 48 no food fast. I tried it to test my keto-adapted state. My last meal was Thursday morning at 7am. I ate salmon with guacamole and steamed broccoli with butter. I also consumed a very fat filled blended coffee. For the next 50 hr actually I ate nothing. The only thing other then water I had was black coffee and herbal teas.
During the fast I felt pretty good. I would say my energy level was down about 15%. The 2 days I worked full days and had plenty of energy. Saturday morning before breaking the fast I tested my blood and urine ketone levels. Blood ketone levels were high at 4.8 and urine levels were high too. I really like doing this 48 hour fast.
I noticed after the fast my body felt reset. I felt less craving and more controlled eating. I am thinking about doing this once a month or ever two months.